12v electric woes.

[Mynstral]

Hi all. We store our van in a secure storage facility away from home. Stupidly I left the electric master switch on and it ran the battery down. I have removed the battery and charged it up. When I reattach the battery it blows the main 25a fuse. Any ideas?

With the car connected we get interior lights etc, don't know about 240v as there are none at storage facility. But it's fitted with a self levelling system and this won't work. So it's now become a static.

It is a 2015 Buccaneer Schooner.

Regards Myn.

 

[Kevin2306]

Hi Myn

Have you tried fitting an alternative battery and seeing how the fuse reacts?
One other thought, have you connected it correctly, I would imagine reverse polarity would take the fuse out?

Kevin

 

[Mynstral]

Hi Kevin, yes. I originally swapped the battery over with another, but I didn't check the polarity. I replaced the fuses and original battery after charging at home. This is when if started blowing fuses.

If there is a short somewhere where is it likely to be? Is there a 'vulnerable spot'? Solar control unit?

Regards Myn.

 

[Woodentop]

Some electronic devices have reverse polarity protection. It can be a diode in series with the supply (preferred) or a reversed diode across the input so that a reversed polarity connection blows the fuse. However if the fuse is too big and the diode insufficiently rated the diode may blow (go short circuit) before the fuse blows. The only things in a caravan that I can think of that may be so protected are USB chargers, solar power control, or the car radio.

Question: when the battery is connected and the fuse blows, is the caravan main switch off?

 

[Mynstral]

Hi Woodentop. From memory every thing was off i.e. Master switch in off position.

Regards Myn.

 

[Hutch]

Myn, remember even with the "Master" switches off items like fridge power and radio power is still left connectted, when I leave our Coachman in storage I pull the 20 amp battery Fuse which shuts down everything except the alarm system.
Gòd luck
Hutch.

 

[Woodentop]

Myn, remember even with the "Master" switches off items like fridge power and radio power is still left connectted, when I leave our Coachman in storage I pull the 20 amp battery Fuse which shuts down everything except the alarm system.
Gòd luck
Hutch.

Sorry Hutch but that's not correct.

The fridge only runs off 12V when powered by the car. If, and I say IF, it has electronic control the power to it will still be controlled by the master switch, as indeed will be the radio. I have never yet found a caravan manufacturer that has a separate memory support supply to the radio, so again if the master is off so will be the radio.

 

[VicMallows]

I have never yet found a caravan manufacturer that has a separate memory support supply to the radio, so again if the master is off so will be the radio.

Even more annoying with the horrid SONY radio fitted in my Elddis is that when you turn the master-switch back on, the radio powers up by default. Since the radio is hidden in an overhead locker it will happily sit there forever displaying its start-up screen .... and drawing a ridiculous 0.72A hmy: (It has, of course, now been suitably modified).

 

[Hutch]

I have never yet found a caravan manufacturer that has a separate memory support supply to the radio, so again if the master is off so will be the radio.

Even more annoying with the horrid SONY radio fitted in my Elddis is that when you turn the master-switch back on, the radio powers up by default. Since the radio is hidden in an overhead locker it will happily sit there forever displaying its start-up screen .... and drawing a ridiculous 0.72A hmy: (It has, of course, now been suitably modified).

Woodentop, sorry mate, my Coachman VIP 2013, even with the master switch off, the fridge still has power to the electronic control, the radio still has power and also the Awning /door light, thats why I have to pull the 20 amp fuse to stop the battery from being slowly pulled down if left for about 6 weeks.j

 

[otherclive]

I have never yet found a caravan manufacturer that has a separate memory support supply to the radio, so again if the master is off so will be the radio.

Even more annoying with the horrid SONY radio fitted in my Elddis is that when you turn the master-switch back on, the radio powers up by default. Since the radio is hidden in an overhead locker it will happily sit there forever displaying its start-up screen .... and drawing a ridiculous 0.72A hmy: (It has, of course, now been suitably modified).

n

My radio, JVC, does the same and I have to remember to open the cupboard and power it off. Must be a feature on a number of different caravan makes. Strange though as its against normal logic.

 

[VicMallows]

It's because, as Woodentop stated, caravan manufacturers don't provide a permanent feed to the circuit which maintains the radio's memory when the main supply ('ignition' in a car) is turned off. (usually a yellow wire).

This memory circuit only consumes about 1mA .....but why it is necessary at all is beyond me when practically everything else on the planet manages perfectly well with passive memory and consumes absolutely nothing when switched off.

 

[Craigyoung]

Mine's the same, power on , radio on , very annoying

 

[waffler]

The connections that might stay live when the master is off are: radio for memory, fridge gas ignitor, alarm feed and solar panel unit. Firstly take your battery to reputable dealer and have them check it. The problem may be there. Then take out all 12 volt fuses carefully. Don't forget the solar panel fuse which may not be in the consumer unit. Now connect the tested battery. Replace each fuse in turn and see what happens. If there is a problem with a particular component then the fuse will blow either as it is inserted or the main fuse will go. You now know where the problem is. At this point consult an expert. If with no 12 v fuses in place the main fuse goes when you reconnect there must be a problem in wiring somewhere. My suspicion is an electronic unit somewhere that has developed a short. Number one suspect is solar panel control unit.

 

[Dustydog]

Over the years Manufacturers keep rewriting their wiring diagrams
Our Wyoming from Bailey , master 12 v isolates everything except the Dometic fridge integral light. You have to leave the door open on its ajar setting when stored. Unless the fridge control switch is turned off the light remains on and.....flattens the battery.
So when is a Master switch a Master switch :S

 

[Hutch]

My fridge internal light stays on even when you close the door.

 

[otherclive]

My fridge internal light stays on even when you close the door.

Mine doesn't as I took the bulb out just to prevent and inadvertent battery mishaps.Fridge doesn't need lighting anyway.

 

[bertieboy1]

Mynstral,
Check you are connecting the battery correctly ie the polarity is correct.(+ve to +ve and -ve to -ve)
A fuse (or any electrical protection device) will only operate for a fault further down the circuit..A fault battery will not operate the fuse.(the battery is fitted before the fuse).

 

[Woodentop]

Curiously, when the master switch is off the fridge light is off, but even if the master is off and I connect the EHU the light comes on.
Hmmmm........

 

[YorkieF]

Have you checked that the positive on the battery is actually positive. I've known batteries to have reversed polarity.